Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$128.94	9.849%	$141.6393	$141.64	$141.65	$141.60
Purchase #2	$102.79	8.114%	$111.1304	$111.13	$111.15	$111.10
Purchase #3	$36.59	12.197%	$41.0529	$41.05	$41.05	$41.10
Purchase #4	$197.55	12.833%	$222.9016	$222.90	$222.90	$222.90
Purchase #5	$117.79	11.644%	$131.5055	$131.51	$131.50	$131.50
Purchase #6	$220.51	3.445%	$228.1066	$228.11	$228.10	$228.10
Purchase #7	$169.95	7.503%	$182.7013	$182.70	$182.70	$182.70
7 purchase totals =	$974.12		$1,059.0376	$1,059.04	$1,059.05	$1,059.00